I. Field of the Invention
The present invention relates generally to a melt tank for processing molded parts.
II. Description of the Prior Art
In the manufacture of molded parts having internal recesses or passageways, a core is first constructed corresponding in shape to the internal recesses or passageways. This core, furthermore, is constructed of a material having a relatively low melting point. In industrial applications, the core is typically constructed of a metallic composition having a low melting temperature, e.g. 360.degree. F.
After the core is formed, the material forming the part is cast over the core and allowed to harden. In order to complete the molded part after hardening, it is necessary to remove the core material from the internal recesses and passageways of the molded part.
In industrial applications, the molded part with the core material still filling the internal passageways and chambers of the molded part is placed in a pallet and then pallets are loaded in the cartridge which, in turn, is placed in a melt tank. The melt tank is maintained at a temperature sufficiently high to melt the core material from the molded parts. Once melted, the core material evacuates from the internal recesses and passageways of the molded part and is collected at the bottom of the melt tank for subsequent reuse in a molding operation.
These previously known melt tanks have typically comprised rectangular structures having a conveyor system extending around the entire bottom of the melt tank. The cartridges are then placed on the conveyor and then conveyed along the outer periphery of the rectangular tank which, in turn, is filled with a heated liquid. These previously known melt tanks, such as a perimeter roller system, a monorail system and a Bachman system, however, have proven disadvantageous in a number of different respects.
One disadvantage of these previously known melt tanks is that, since the conveyor system is contained within and at the bottom of tank, maintenance on the conveyor system requires that the entire tank be evacuated and cooled before maintenance on the conveyor system can be initiated. This disadvantageously results in excessive downtime for the melt tank especially in the case of a monorail system.
A still further disadvantage of these previously known melt tanks is that, since the cartridges are conveyed in a rectangular pattern, a turning conveyor mechanism is required at each corner of the rectangular tank in order to transfer the cartridges from one side of the conveyor tank to the next adjacent side. These turning mechanisms not only increase the overall cost of the melt tank, but also require periodic maintenance. Such maintenance, in turn, also requires that the melt tank be drained and cooled prior to initiating the maintenance.
A still further disadvantage of these previously known melt tanks is that several separate conveyor mechanisms are required, i.e. one for each side of the rectangular tank.
A still further disadvantage of these previously known systems is that a large volume of the melting liquid is required due to the design of the tank. The melting liquid, i.e. lutron, however, is very expensive.